JPH08318491A - Work phase detecting method - Google Patents

Abstract

PURPOSE: To efficiently detect the phase of a work having the rugged section such as a weather strip for an automobile which is held by a holder fitted to a robot by using an optical measuring instrument provided with a slit light source and a photographing tool to photograph the light cutting line described by the slit light irradiated on the work. CONSTITUTION: The pattern of the light cutting line image is categorized based on the pattern change of the light cutting line image when an optical measuring instrument 1 and a work W are relatively turned around the axis of the work, and the difference in angle from the reference phase of the work is obtained in advance when the pattern of the light cutting line image is changed to the different category. The optical measuring instrument 1 and the work W are relatively turned around while the work W is held by a holder 3, and the rotational angle at the time of change to the category of the different pattern of the light cutting line image is detected. The holding phase of the work W is calculated from the detected rotational angle and the difference in angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a work phase detecting method for detecting a holding phase of a work such as a weather strip for automobiles and an opening trim having an uneven cross section when held by a holder. Regarding

[0002]

2. Description of the Related Art Conventionally, weather strips and opening trims have been attached by hand, but it is also possible to hold the weather strips and the like by a holder attached to the operating end of the robot to automate the attachment work. ing.

The weather strip and the opening trim are provided with a recess for mounting on the vehicle body on one side of the periphery, and in order to automate the mounting work of the work such as the weather strip, the recess should be oriented in a predetermined direction. It is necessary to make the holder hold the work in a phase-determined state. In this case, hold the work once with the holding tool at an arbitrary phase,
It is possible to detect the holding phase of the work and then hold the work again at a predetermined phase.

By the way, conventionally, an optical measuring device comprising a slit light source and an image pickup device arranged in a predetermined positional relationship is used, and the light cutting line drawn by the slit light emitted from the slit light source to the work is imaged by the image pickup device. There is known a light cutting method for measuring the shape and position of a work based on a light cutting line image appearing on the screen of an image pickup device (see Japanese Patent Laid-Open No. 62-272106).

[0005]

The holding phase of a work, such as a weather strip, having a cross-sectional shape with projections and depressions is held in a non-contact manner by using the above-mentioned optical cutting method. It is possible. However, in the measurement of a work using the conventional light cutting method, the coordinates of the point on the slit light surface corresponding to each point of the light cutting line image appearing on the screen of the image pickup device are obtained to determine the cross-sectional shape and position of the work. Although the calculation is performed and the holding phase of the work can be detected from the directionality of the cross-sectional shape of the work, the calculation process takes time. Therefore, it is difficult to apply the conventional optical cutting method as it is to the phase detection in the automatic work assembly process in which the cycle time is restricted. In view of the above points, an object of the present invention is to provide a method capable of detecting a holding phase of a work in a shorter time by using a light cutting method.

[0006]

In order to achieve the above object,
The present invention is a phase detection method for detecting a holding phase of a work when a work having a cross-sectional shape with unevenness is held by a holding tool, and is configured by arranging a slit light source and an imager in a predetermined positional relationship. In the method of detecting the holding phase of the work based on the light cutting line image appearing on the screen of the imager, by using the optical measuring device, the imager captures the light cutting line drawn by the slit light emitted from the slit light source to the work. , The pattern of the optical cutting line image is typified based on the pattern change of the optical cutting line image due to the relative rotation of the optical measuring device and the work around the axis line, and the pattern of the optical cutting line image is changed to a different type. The angle difference from the reference phase of the workpiece at that time is obtained in advance, and while the optical measuring device and the workpiece are imaged while the optical cutting line is being held, the workpiece is held by the holder and relatively rotated around the axis of the workpiece. hand Detecting the rotation angle of the change time to different types of patterns of light section line image, determine the retention phase of the workpiece from the said angular difference between the detected rotation angle, and wherein the.

[0007]

The operation of the present invention will be described by taking as an example the case where the work has a sectional shape having a recess at one location in the circumferential direction. When the workpiece is rotated relative to the optical measuring device from the state in which the concave portion faces rearward, the optical cutting line images are continuous 1 corresponding to general portions other than the concave portion of the workpiece until the concave portion faces right side. Although it becomes a linear image of the book, when the work rotates slightly from the state where the recess is oriented right side, the slit light is also incident on the rear side surface of the recess, and the light cutting line image corresponds to the general part of the work. The image and the image corresponding to the rear surface of the concave portion are divided into two. Therefore, the pattern of the light section line image is 1
The angle from the reference phase of the work (for example, the phase in which the recess faces right behind) when the pattern is categorized into the first type that becomes two and the second type that has two images and changes to the second type. If the difference is obtained in advance, the optical measuring device and the workpiece are relatively rotated, and the rotation angle at the time when the optical cutting line image changes from the first type to the second type is detected. The deviation angle of the holding phase from the reference phase can be obtained.

Even when the conventional light cutting method is used as it is, the direction cannot be determined if the light cutting line image is only an image corresponding to the general part of the work. It is necessary to rotate the optical measuring device and the workpiece relative to each other until the corresponding image appears. Then, the phase of the work is obtained by a complicated calculation process from the coordinates of each point of the image corresponding to the recess imaged in this state. On the other hand, according to the present invention, it suffices to determine which type the optical cutting line image belongs to and specify the time point of change to a different type. Here, the type determination can be performed by a simple process. The holding phase of the work can be detected in a short time.

[0009]

EXAMPLE An example in which the present invention is applied to the phase detection of a work W having an automobile weatherstrip and having a sectional shape as shown in FIG. 4 will be described.

With reference to FIG. 1, reference numeral 1 is an optical measuring device constituted by mounting a slit light source 11 and an image pickup device 12 composed of a CCD camera on a column 10, and a holder attached to the working end of the robot 2. After the work W is held at an arbitrary phase by 3, the work W is conveyed to a predetermined measurement position facing the optical measuring device 1 by the operation of the robot 2.

The slit light source 11 and the image pickup device 12 have an optical surface of slit light emitted from the slit light source 11 (hereinafter,
The optical axis of the image pickup device 12 is attached to the support column 10 in a predetermined positional relationship such that the optical axis of the image pickup device 12 obliquely intersects the slit light surface). In the illustrated example, the slit light source 11 is arranged so that the slit light surface faces obliquely upward, and the image pickup device 12 is arranged above the slit light source 11 so as to match the horizontal line obliquely intersecting the slit light surface. The slit light surface may be horizontal, and the optical axis of the image pickup device 12 may be tilted in the vertical direction so as to be oblique to the slit light surface. A second holder 13 for temporarily holding the work W is attached to the upper end of the column 10. Reference numeral 14 in the drawing is an image processing apparatus.

The robot 2 has a base 2 as shown in FIG.
0, a shoulder portion 21 that is rotatable around a vertical first axis 2a, an upper arm portion 22 that is vertically swingable around a second axis 2b that is horizontal with respect to the shoulder portion 21, and an upper arm. An elbow portion 23 which is rotatable about the third axis 2c with respect to the portion 22, and an elbow portion 2
3, the lower arm portion 24 that can swing about the fourth axis 2d
And a wrist 25 that is rotatable about the fifth axis 2e with respect to the lower arm portion 24, and a sixth axis 2f and a seventh axis 2 with respect to the wrist 25.
It is configured by a 7-axis articulated robot including a tool holder 26 that can be swung and swung about g. The holder 3 is attached to the tool holder 26, and the workpiece W is set to the posture of the holder 3. While maintaining the hanging posture, the work W is moved around its axis by the movement of each axis of the robot 2.
It was made possible to rotate by 0 °.

When the holding phase of the workpiece W is detected by the holder 3, the workpiece W is conveyed to the measuring position, and then the slit light source 11 irradiates the workpiece W with slit light so that the surface of the workpiece W is drawn by the slit light. The work W is rotated around its axis while the optical cutting line is imaged by the imager 12.

At this time, the work W is displayed on the screen of the image pickup device 12.
A light-section line image corresponding to the cross-sectional shape when the light is cut along the slit light surface appears, and the pattern of this image changes as shown in FIG. This is the work W
As an example, the case where each of A, C, D, and F of FIG. 4 faces the optical measuring device 1 side, that is, the state where the optical measuring device 1 exists at the position of θ ₀ in FIG. 4 is set as the reference phase. Will be described in detail.

At the reference phase, A, C, D and F of the work W are
The slit light is radiated to each part of FIG.
As shown in (a), the pattern is divided into three parts: an image a corresponding to the A portion, continuous images c and d corresponding to the C and D portions, and an image f corresponding to the F portion. Here, rotating the work W is equivalent to revolving the optical measuring device 1 around the axis of the work W, and when the measuring device 1 exceeds the position of θ ₁ in FIG. The slit light is no longer radiated to the part A of FIG.
As shown in FIG. 3, the pattern is divided into two, an image c corresponding to the C portion and continuous images f and g corresponding to the F and G portions.
When the optical measuring device 1 goes beyond the position of θ ₂ in FIG. 4, the slit light is not radiated to the C portion of the work W, and the optical cutting line image is shown in the F and G portions as shown in FIG. 3C. There will be one corresponding continuous image f, g. After that, as the work W rotates, the light section line image becomes continuous images g and h corresponding to the G and H portions, as shown in FIG.
As shown in (e), the image h corresponds to the H portion, but the image is maintained in one pattern in both cases. Optical measuring device 1
4 exceeds the position of θ ₃ in FIG. 4, the slit light is irradiated to the B portion of the work W, and the light cutting line image shows images h and B corresponding to the H portion as shown in FIG. The pattern is divided into two, an image b corresponding to a copy. The optical measuring device 1 is shown in FIG.
When the position of θ ₄ is exceeded, the slit light is also radiated to the E part of the work W, and the light cutting line image is formed on the image h corresponding to the H part and the B part as shown in FIG. 3 (g). Corresponding image b and E
A pattern divided into three parts is formed into an image e corresponding to a part. When the optical measuring device 1 exceeds the position of θ ₅ in FIG. 4, slit light is irradiated to the A portion of the work W, and the abutting ends of the C portion and the D portion, and the light cutting line image is shown in FIG. As shown in (h),
It becomes one continuous image a, b, c, d, e corresponding to each part of A, B, C, D, E. When the optical measuring device 1 goes beyond the position of θ ₆ in FIG. 4, the slit light is no longer emitted to the E portion, and the light section line image is A, as shown in FIG.
Continuous images a, b, c, d corresponding to the respective parts B, C, D
And an image f corresponding to the F portion is divided into two patterns. Then, when the beam returns to the reference phase, the slit light is no longer emitted to the B portion, and the light section line image is as described above.
It becomes a divided pattern.

When the optical measuring device 1 is revolved counterclockwise from the position of θ ₀ (the work is rotated clockwise from the reference phase), the pattern of the light section line image is typified by the number of images. And changes as shown in the table below.

[0017] As is clear from this table, when the optical measuring device 1 is rotated in the counterclockwise direction, the point where the number of images changes from three types to two types is only θ ₁ . The only point where the number changes from two types to one type is θ ₂ , and the only point where the number of images changes from three types to one type is θ ₅ . Therefore, the angle difference between θ ₀ and θ ₁ (hereinafter, referred to as θ ₁ ) and the angle difference between θ ₀ and θ ₂ (hereinafter,
This is referred to as θ ₂ ) and the angle difference between θ ₀ and θ ₅ (hereinafter, referred to as θ ₅ ) is calculated, and the image processing device 14
To be stored.

When detecting the phase of the work W, the holder 3
Is made to face the optical measuring device 1, that is, the state where the optical measuring device 1 exists at the position of θ ₀ with respect to the holder 3 shown by a virtual line in FIG. The rotation of the holder 3 causes the work W to rotate clockwise about its axis. Then, every time the work W is rotated by a predetermined unit angle, the image data of the image pickup device 12 is transmitted to the image processing device 14, the image is binarized, noise is removed, and the binarized image is labeled. , Count the number of light section line images.

Then, as shown in FIG. 5, it is determined whether or not the number of images has changed from the previous time (S1), and when it changes, the rotation angle θ at the time of change is detected (S2), and the number of images is changed. It is discriminated whether the change of 3 changes from 3 to 2, the change from 2 to 1, the change from 3 to 1, or any other change (S3 to S5).

Here, in order to mount the work W on the vehicle body,
The work W is held by the holder 3 with the H part facing you (when the holder 3 is oriented toward the origin, the work W is in the reference phase), and between the C and D parts facing forward with respect to the holder 3. It is necessary to insert the mounting flange on the vehicle body side, and assuming that this phase is the normal holding phase of the work W, if the holding phase is normal, the image of the light cutting line image when the holder 3 is rotated by θ ₁ from the origin. Changes from 3 to 2, the number of images changes from 2 to 1 when rotated by θ ₂ , and the number of images changes from 3 to 1 when rotated by θ ₅ . The deviation angle Δθ of the holding phase of the workpiece W from the normal phase (the deviation direction is positive when the deviation direction is clockwise and the negative direction when the deviation direction is counterclockwise) is measured from the origin of the holder 3 in the clockwise direction. When the rotation angle is θ and the number of images changes from 3 to 2, Δθ = θ ₁ −θ, and when the number of images changes from 2 to 1, Δθ = θ ₂ −θ When the number of images changes from 3 to 1, Δθ = θ ₅ −θ, and Δθ can be obtained from θn (n = 1, 2, 5) and θ.

Therefore, when the number of images changes from 3 to 2, θn is set to θ ₁ (S6), and when the number of images changes from 2 to 1, θn is set to θ ₂ ( S7), the number of images is 3
When changing from pieces to one is a θn and θ ₅ (S8),
The deviation angle Δθ of the holding phase of the work W from the normal phase is calculated from the following equation, Δθ = θn−θ (S9).

In this embodiment, the number of images is 3 to 2
Change from one, two to one, three to one,
Although the phase detection process of the work W is finished when Δθ is calculated once, the phase detection process may be continued until Δθ is calculated three times and the average value thereof may be obtained.
Even in this case, since the number of images can be detected in a short time by the labeling process, the processing time does not become as long as the left.

When Δθ is calculated as described above, the work W is delivered to the second holder 13, the holder 3 is rotated clockwise by Δθ, and then the work W is again held by the holder 3. Hold. In this state, the work W is held by the holder 3 in the normal phase, and the work W
Can be mounted on the vehicle body.

When the number of images changes from three to two, from two to one, or from three to one, the phase of the work W changes from the reference phase to the clock. There are deviations of θ ₁ , θ ₂ , and θ _{5 in the respective} directions. Therefore, the rotation angle θ of the workpiece W at these changing points is detected, and the workpiece W is rotated counterclockwise from this angular position by θ ₁ , θ ₂ , and θ ₅ , respectively. The work W becomes the reference phase by rotating θ ₅ . Then, when the work W is returned to the reference phase, the work W is held by the second holder 13
When the holder 3 is handed over to the holder 3, and the workpiece W is held by the holder 3 again by rotating the holder 3 in a direction directly facing the optical measuring device 1, that is, returning to the origin. To be done. This method uses the rotation angle θ at the time of image change.
And θn (n = 1, 2, 5), the work W is reversed from θ by θn, although the deviation angle Δθ from the normal phase of the work W is calculated directly. The deviation angle Δθ is indirectly obtained in this form, and this also belongs to the technical scope of the present invention.

Further, the robot 2 is exclusively used for phase detection, and a robot for mounting a work is separately provided so that the holder 3 to the second
After the workpiece W is delivered to the holder 13 at the reference phase, the workpiece W is held by the holder attached to the working end of the workpiece mounting robot in a state of being directly opposed to the optical measuring device 1. You can According to this, the phase of the next work W can be detected during the work of mounting the work W, and the work efficiency can be further improved.

[0026]

As is apparent from the above description, according to the present invention, the holding phase of the work can be detected efficiently in a short time, and the work can be applied to the automatic assembly process of the work whose cycle time is restricted. Becomes

[Brief description of drawings]

FIG. 1 is a perspective view of an example of equipment used for implementing the present invention.

FIG. 2 is a perspective view of a robot included in the above equipment.

3 (a) to (i) are views showing a pattern change of an optical cutting line image accompanying rotation of a work.

FIG. 4 is a diagram showing a change in relative position of the optical measuring device with rotation of a work.

FIG. 5 is a flowchart showing a work phase detection program.

[Explanation of symbols]

1 Optical Measuring Device, 11 Slit Light Source, 12
Imager 2 Robot, 3 Holder, W
work

Claims (1)

[Claims] 1. A phase detection method for detecting a holding phase of a work when a work having a cross-sectional shape having irregularities is held by a holding tool, wherein a slit light source and an image pickup device are arranged in a predetermined positional relationship. The optical measuring device is used to image the light cutting line drawn by the slit light emitted from the slit light source to the work with the image pickup device, and the holding phase of the work is detected based on the light cutting line image appearing on the screen of the image pickup device. In the above, the pattern of the optical cutting line image was typified based on the pattern change of the optical cutting line image due to the relative rotation of the optical measuring device and the work around the axis of the work, and the pattern of the optical cutting line image was changed to a different type. When the angle difference from the reference phase of the work is obtained in advance, the optical measuring device and the work are relatively rotated around the axis of the work while holding the work on the holder while imaging the optical cutting line. It And detecting the rotation angle at the time of changing the pattern of the optical cutting line image to a different pattern, and determining the holding phase of the work from the detected rotation angle and the angle difference. .